CN112189318A - Front-loaded sounding reference signal and physical random access channel signal - Google Patents
Front-loaded sounding reference signal and physical random access channel signal Download PDFInfo
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Abstract
Methods, systems, and devices for wireless communication are described. A User Equipment (UE) may identify a gap period after a downlink portion of a Time Division Duplex (TDD) frame. The UE may selectively perform a Clear Channel Assessment (CCA) on a channel of a radio frequency spectrum band based at least in part on the gap period. The UE may transmit at least one of a Sounding Reference Signal (SRS) or a Physical Random Access Channel (PRACH) preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a demodulation reference signal (DMRS), an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
Description
Cross-referencing
This patent application claims the benefit of U.S. provisional patent application No.62/670,206 entitled "Front Loaded Sounding Reference Signal and Physical Random Access Channel Signal" filed by Zhang et al on 11.5.2018 and U.S. patent application No.16/406,469 entitled "Front Loaded Sounding Reference Signal and Physical Random Access Channel Signal" filed by Zhang et al on 8.5.2019, each of which is assigned to the present assignee.
Background
The following relates generally to wireless communications, and more particularly to a front-loaded Sounding Reference Signal (SRS) and a Physical Random Access Channel (PRACH).
Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be able to support communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems, such as Long Term Evolution (LTE) systems, LTE-advanced (LTE-a) systems, or LTE-a Pro systems, and fifth generation (5G) systems that may be referred to as New Radio (NR) systems. These systems may employ techniques such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or discrete fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple-access communication system may include several base stations or network access nodes, each supporting communication for multiple communication devices simultaneously, which may otherwise be referred to as User Equipment (UE).
Some wireless communication systems may support Time Division Duplex (TDD) based frame structures, such as TDD fixed frame periods. Typically, such TDD-based frame structures begin with a first device capturing a channel for a period of time (e.g., a channel occupancy time (CoT), a transmission opportunity (TxOP), etc.) by performing a Clear Channel Assessment (CCA) procedure on the channel. If the CCA procedure is successful, the first device controls the channel for a CoT followed by an idle period. During CoT, the first device may perform downlink transmissions to the second device and/or receive uplink transmissions from the second device. For example, a first device may perform downlink transmissions and provide grants of resources for uplink transmissions to a second device. In some scenarios, a gap period between transmissions (e.g., between downlink and uplink transmissions, between consecutive uplink transmissions, etc.) exceeding a threshold during the CoT may require an additional CCA procedure to be performed by the second device before the uplink transmission occurs. The second device having to perform the additional CCA procedure may delay such uplink transmissions, which may increase latency and require additional resources.
SUMMARY
The described technology relates to improved methods, systems, devices, or apparatuses supporting front-loaded Sounding Reference Signal (SRS) or Physical Random Access Channel (PRACH) preamble transmission. Reference to SRS transmission may refer to SRS transmission, SRS and PRACH preamble transmission, and/or PRACH preamble transmission. In general, the described techniques provide for piggybacking (e.g., during some of the first few symbols of the uplink portion) an SRS or PRACH preamble that uses Frequency Division Multiplexing (FDM) with other reference signals (e.g., demodulation reference signals (DMRS)), uplink data and/or control transmission(s), and/or other random access transmission(s). For example, a first device (such as a base station) may capture an unlicensed or shared channel by performing a CCA procedure or some other Listen Before Talk (LBT) procedure. In some aspects, the channel may be configured as a TDD frame, e.g., such as a fixed frame period based on TDD. The first device may transmit a downlink transmission to a second device (e.g., a User Equipment (UE)) during a downlink portion of a TDD frame. In some aspects, the downlink transmission may include data and/or control information, and in some examples may include a grant of resources for the second device to use to perform uplink transmissions during an uplink portion of a TDD frame. The second device may identify a gap period after the downlink portion of the TDD frame, e.g., a time period between the end of the downlink portion and the beginning of the uplink portion. In some aspects, the second device may selectively perform a CCA procedure on the channel when the gap period exceeds a defined threshold. For example, some wireless communication systems may require the second device to perform a CCA procedure if the gap period exceeds a threshold.
However, aspects of the described techniques may enable the second device to avoid the CCA procedure by ensuring that the gap period does not exceed the threshold or reducing instances in which the gap period exceeds the threshold. For example, the described techniques may piggyback SRS or PRACH preambles during an earlier portion (e.g., during the first few symbols or some symbols of an initial set of symbols of an uplink portion of a TDD frame). Thus, the second device may transmit an SRS or PRACH preamble during the initial symbol set and may FDM the SRS or PRACH preamble with the DMRS, uplink data or control transmission(s), and/or other random access transmission(s). Piggybacking the SRS or PRACH preamble along with other transmissions may provide a mechanism for the second device (or other devices) to communicate early during the uplink portion of the TDD frame and thus minimize the length of the gap period and avoid having to perform additional CCA procedures.
A method of wireless communication at a UE is described. The method can comprise the following steps: identifying a gap period after a downlink portion of a TDD frame; selectively perform a CCA on a channel of a radio frequency spectrum band based on the gap period; and transmitting at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: identifying a gap period after a downlink portion of a TDD frame; selectively perform a CCA on a channel of a radio frequency spectrum band based on the gap period; and transmitting at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
Another apparatus for wireless communication at a UE is described. The apparatus may include means for: identifying a gap period after a downlink portion of a TDD frame; selectively perform a CCA on a channel of a radio frequency spectrum band based on the gap period; and transmitting at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
A non-transitory computer-readable medium storing code for wireless communication at a UE is described. The code may include instructions executable by a processor for: identifying a gap period after a downlink portion of a TDD frame; selectively perform a CCA on a channel of a radio frequency spectrum band based on the gap period; and transmitting at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: a first comb of a resource block is identified, wherein the SRS or PRACH preamble may be transmitted on the first comb of the resource block during an initial set of symbols.
In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the DMRS, or uplink data transmission, or uplink control transmission, or random access transmission may be transmitted on a second comb of resource blocks.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: the DMRS is transmitted from a first set of antenna ports during a first subset of an initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: the DMRS is transmitted from a second set of antenna ports during a second subset of the initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: transmitting an SRS or PRACH preamble frequency domain multiplexed with uplink data transmissions during a first subset of an initial symbol set.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: transmitting, from the set of antenna ports, an SRS or PRACH preamble frequency domain multiplexed with the DMRS during a second subset of the initial set of symbols.
In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the SRS or PRACH preamble and the DMRS may be transmitted on different combs of a resource block.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: an SRS or PRACH preamble is transmitted on a first interlace of a channel bandwidth and a DMRS, or an uplink data transmission, or an uplink control transmission, or a random access transmission is transmitted on a second interlace of the channel bandwidth.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: uplink data transmissions are transmitted on a Physical Uplink Shared Channel (PUSCH).
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: additional uplink data transmissions are transmitted on the PUSCH during one or more symbols occurring after the initial set of symbols.
In some examples of the methods, devices (apparatus), and non-transitory computer-readable media described herein, selectively performing CCA on a channel of a radio frequency spectrum band based on a gap period may include operations, features, means, or instructions to: performing a CCA procedure when a duration of the gap period exceeds a threshold.
In some examples of the methods, devices (apparatus), and non-transitory computer-readable media described herein, selectively performing CCA on a channel of a radio frequency spectrum band based on a gap period may include operations, features, means, or instructions to: transmitting the SRS or the PRACH preamble without performing the CCA procedure when a duration of the gap period may be less than a threshold.
In some examples of the methods, devices (apparatuses), and non-transitory computer-readable media described herein, the initial set of symbols includes one or more symbols immediately following the gap period.
A method of wireless communication at a base station is described. The method can comprise the following steps: performing a CCA on a channel of a radio frequency spectrum band prior to a downlink portion of a TDD frame; performing a downlink transmission during a downlink portion of the TDD frame based on the success of the CCA; and receiving at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
An apparatus for wireless communication at a base station is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: performing a CCA on a channel of a radio frequency spectrum band prior to a downlink portion of a TDD frame; performing a downlink transmission during a downlink portion of the TDD frame based on the success of the CCA; and receiving at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
Another apparatus for wireless communication at a base station is described. The apparatus may include means for: performing a CCA on a channel of a radio frequency spectrum band prior to a downlink portion of a TDD frame; performing a downlink transmission during a downlink portion of the TDD frame based on the success of the CCA; and receiving at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
A non-transitory computer-readable medium storing code for wireless communication at a base station is described. The code may include instructions executable by a processor for: performing a CCA on a channel of a radio frequency spectrum band prior to a downlink portion of a TDD frame; performing a downlink transmission during a downlink portion of the TDD frame based on the success of the CCA; and receiving at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: a first comb of a resource block is identified, wherein the SRS or PRACH preamble may be received on the first comb of the resource block during an initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: identifying a second comb of the resource block and receiving one or more of a DMRS, or an uplink data transmission, or an uplink control transmission, or a random access transmission on the second comb of the resource block.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: the DMRS is received from a first set of antenna ports during a first subset of an initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: the DMRS is received from a second set of antenna ports during a second subset of the initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: an SRS or PRACH preamble frequency domain multiplexed with uplink data transmissions is received during a first subset of an initial symbol set.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: receiving an SRS or PRACH preamble frequency domain multiplexed with a DMRS from a set of antenna ports during a second subset of the initial set of symbols.
In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the SRS or PRACH preamble and the DMRS may be received on different combs of a resource block.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: the SRS or PRACH preamble is received on a first interlace of a channel bandwidth and the DMRS, or uplink data transmission, or uplink control transmission, or random access transmission is received on a second interlace of the channel bandwidth.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: an uplink data transmission is received on a PUSCH.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: additional uplink data transmissions are received on the PUSCH during one or more symbols occurring after the initial set of symbols.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: the method may include receiving an SRS or PRACH preamble from a first device and receiving a DMRS, or an uplink data transmission, or an uplink control transmission, or a random access transmission from a second device, the second device being different from the first device.
Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, devices, or instructions to: receiving at least one of an SRS or PRACH preamble and a DMRS, or an uplink data transmission, or an uplink control transmission, or a random access transmission from the same device.
In some examples of the methods, devices (apparatuses), and non-transitory computer-readable media described herein, the initial set of symbols includes one or more symbols immediately following the gap period.
Brief Description of Drawings
Fig. 1 illustrates an example of a wireless communication system that supports a front-loaded Sounding Reference Signal (SRS) and a Physical Random Access Channel (PRACH) preamble, in accordance with aspects of the present disclosure.
Fig. 2 illustrates an example of a Time Division Duplex (TDD) frame configuration supporting a front-loaded SRS and PRACH, in accordance with aspects of the present disclosure.
Fig. 3 illustrates an example of a Resource Block (RB) configuration supporting a front-loaded SRS and PRACH, in accordance with aspects of the present disclosure.
Fig. 4 illustrates an example of an RB configuration supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure.
Fig. 5 illustrates an example of an interleaving configuration supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure.
Fig. 6 illustrates an example of a process to support a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure.
Fig. 7 and 8 show block diagrams of apparatuses supporting a front loading SRS and PRACH, according to aspects of the present disclosure.
Fig. 9 illustrates a block diagram of a communication manager supporting a piggybacked SRS and PRACH in accordance with aspects of the present disclosure.
Fig. 10 shows an illustration of a system including devices supporting a preamble SRS and a PRACH, in accordance with aspects of the present disclosure.
Fig. 11 and 12 show block diagrams of apparatuses supporting a front-loaded SRS and a PRACH, according to aspects of the present disclosure.
Fig. 13 illustrates a block diagram of a communication manager supporting a piggybacked SRS and PRACH in accordance with aspects of the present disclosure.
Fig. 14 shows an illustration of a system including devices supporting a piggybacked SRS and a PRACH, in accordance with aspects of the present disclosure.
Fig. 15 to 18 show flow diagrams illustrating methods of supporting a front-loaded SRS and a PRACH, according to aspects of the present disclosure.
Detailed Description
Some wireless communication systems may be configured with a Time Division Duplex (TDD) based frame structure over a shared or unlicensed radio frequency spectrum band. For example, a first device, such as a base station, may capture a channel in a shared or unlicensed band by performing a Clear Channel Assessment (CCA) procedure on the channel. Once captured, the first device may perform downlink and/or uplink communications on the channel, e.g., for a time period during corresponding downlink and uplink portions of the TDD frame. In some cases, transmissions during a TDD frame may not require an additional CCA procedure unless there is a gap period that extends beyond a defined time period. If the gap period (e.g., between downlink and uplink, between uplink and downlink transmissions, between consecutive uplink or downlink transmissions, etc.) exceeds a defined time period or threshold, the respective device must perform an additional CCA procedure during the TDD frame. This increases latency and utilizes unnecessary resources.
Aspects of the present disclosure are initially described in the context of a wireless communication system. In general, aspects of the present disclosure provide a mechanism in which a second device (e.g., a User Equipment (UE)) may avoid having to perform an additional CCA procedure by minimizing a gap period between downlink and uplink portions of a TDD frame. For example, a first device (e.g., a base station) may capture a channel by performing a CCA procedure on the channel. In some aspects, the channel may be a shared or unlicensed radio frequency spectrum band. The first device may capture the channel for a period of time (e.g., capture channel occupancy time (CoT), transmission opportunity (TxOP), etc.). The first device may perform downlink transmission(s) on the channel during corresponding downlink portion(s) of the TDD frame. In some aspects, the downlink transmission may include a grant of resources for the second device to use for uplink transmission on the channel. In some aspects, the downlink transmission may simply provide an indication of the time at which the second device may use the channel for uplink transmission (e.g., an indication of the uplink portion of a TDD frame may be provided).
In some aspects, the second device may identify a gap period after a downlink portion of the TDD frame. For example, the gap period may comprise the time between the end of the downlink portion and the beginning of the uplink portion. In some aspects, the second device may selectively perform a CCA procedure on the channel based on the gap period. For example, the second device may perform a CCA procedure when the gap period exceeds a defined threshold (e.g., longer than a defined time period). However, when the gap period does not exceed the defined threshold, the second device may skip performing the CCA procedure on the channel. In some aspects, this may include the second device transmitting the SRS or PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame. For example, the gap period may include a first symbol, or first and second symbols, of a TDD frame, and the SRS or PRACH preamble may be transmitted in the second symbol, or second and third, etc., symbols, of the TDD frame. In some aspects, piggybacking SRS or PRACH preamble during an initial symbol set of an uplink portion of a TDD frame may minimize the duration of a gap period and thus reduce the opportunities for performing CCA procedures. In some aspects, the second device may also FDM the SRS or PRACH preamble with other transmissions (from the second device or from other devices operating on the channel). For example, the second device may FDM the SRS or PRACH preamble with demodulation reference symbol(s) DMRS, uplink control or data transmission(s), or other random access transmission(s). In some aspects, FDM may be per tone based, per comb tooth based, per interlace based, and/or the like.
Aspects of the present disclosure are further illustrated and described by and with reference to apparatus diagrams, system diagrams, and flow charts related to front-loaded SRS.
Fig. 1 illustrates an example of a wireless communication system 100 supporting a front-loaded SRS and PRACH, in accordance with aspects of the present disclosure. The wireless communication system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE-advanced (LTE-a) network, an LTE-a Pro network, a New Radio (NR) network, or an NR shared spectrum (NR-SS) network. In some cases, wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low cost and low complexity devices.
The base station 105 may wirelessly communicate with the UE 115 via one or more base station antennas. The base stations 105 described herein may include or may be referred to by those skilled in the art as base transceiver stations, radio base stations, access points, radio transceivers, node bs, evolved node bs (enbs), next generation node bs or gigabit node bs (any of which may be referred to as gnbs), home node bs, home evolved node bs, or some other suitable terminology. The wireless communication system 100 may include different types of base stations 105 (e.g., macro cell base stations or small cell base stations). The UEs 115 described herein may be capable of communicating with various types of base stations 105 and network equipment, including macro enbs, small cell enbs, gbbs, relay base stations, and so forth.
Each base station 105 may be associated with a particular geographic coverage area 110, supporting communication with various UEs 115 in that particular geographic coverage area 110. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via a communication link 125, and the communication link 125 between the base station 105 and the UE 115 may utilize one or more carriers. The communication links 125 shown in the wireless communication system 100 may include uplink transmissions from the UEs 115 to the base stations 105 or downlink transmissions from the base stations 105 to the UEs 115. Downlink transmissions may also be referred to as forward link transmissions, and uplink transmissions may also be referred to as reverse link transmissions.
The geographic coverage area 110 of a base station 105 may be divided into sectors that form only a portion of the geographic coverage area 110, and each sector may be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other type of cell, or various combinations thereof. In some examples, the base stations 105 may be mobile and thus provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and the overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.
The term "cell" refers to a logical communication entity for communicating with a base station 105 (e.g., on a carrier) and may be associated with an identifier to distinguish between neighboring cells (e.g., Physical Cell Identifier (PCID), Virtual Cell Identifier (VCID)) operating via the same or different carriers. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., Machine Type Communication (MTC), narrowband internet of things (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of devices. In some cases, the term "cell" may refer to a portion (e.g., a sector) of geographic coverage area 110 over which a logical entity operates.
Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may provide automated communication between machines (e.g., communication via machine-to-machine (M2M)). M2M communication or MTC may refer to data communication techniques that allow devices to communicate with each other or with the base station 105 without human intervention. In some examples, M2M communications or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay the information to a central server or application that may utilize the information or present the information to a person interacting with the program or application. Some UEs 115 may be designed to collect information or implement automated behavior of a machine. Examples of applications for MTC devices include: smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, field survival monitoring, weather and geographic event monitoring, queue management and tracking, remote security sensing, physical access control, and transaction-based business charging.
Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communications (e.g., a mode that supports unidirectional communication via transmission or reception but does not simultaneously transmit and receive). In some examples, half-duplex communication may be performed with a reduced peak rate. Other power saving techniques for the UE 115 include entering a power saving "deep sleep" mode when not engaged in active communication, or operating on a limited bandwidth (e.g., according to narrowband communication). In some cases, the UE 115 may be designed to support critical functions (e.g., mission critical functions), and the wireless communication system 100 may be configured to provide ultra-reliable communication for these functions.
In some cases, the UE 115 may also be able to communicate directly with other UEs 115 (e.g., using peer-to-peer (P2P) or device-to-device (D2D) protocols). One or more UEs of the group of UEs 115 communicating with D2D may be within the geographic coverage area 110 of the base station 105. The other UEs 115 in the group may be outside the geographic coverage area 110 of the base station 105 or otherwise unable to receive transmissions from the base station 105. In some cases, groups of UEs 115 communicating via D2D may utilize a one-to-many (1: M) system, where each UE 115 transmits to every other UE 115 in the group. In some cases, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving base stations 105.
The base stations 105 may communicate with the core network 130 and with each other. For example, the base station 105 may interface with the core network 130 over a backhaul link 132 (e.g., via S1 or other interface). The base stations 105 may communicate with each other over backhaul links 134 (e.g., via X2 or other interface) directly (e.g., directly between base stations 105) or indirectly (e.g., via the core network 130).
The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an Evolved Packet Core (EPC) that may include at least one Mobility Management Entity (MME), at least one serving gateway (S-GW), and at least one Packet Data Network (PDN) gateway (P-GW). The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be communicated through the S-GW, which may itself be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to network operator IP services. The operator IP services may include access to the internet, intranet(s), IP Multimedia Subsystem (IMS), or Packet Switched (PS) streaming services.
At least some network devices, such as base stations 105, may include subcomponents, such as access network entities, which may be examples of Access Node Controllers (ANCs). Each access network entity may communicate with UEs 115 through a number of other access network transport entities, which may be referred to as radio heads, intelligent radio heads, or transmission/reception points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., base station 105).
The wireless communication system 100 may operate using one or more frequency bands, typically in the range of 300MHz to 300 GHz. Generally, the 300MHz to 3GHz region is referred to as the Ultra High Frequency (UHF) region or the decimeter band because the wavelengths range from about 1 decimeter to 1 meter long. UHF waves can be blocked or redirected by building and environmental features. However, these waves may penetrate a variety of structures sufficiently for a macro cell to provide service to a UE 115 located indoors. UHF-wave transmission can be associated with smaller antennas and shorter ranges (e.g., less than 100km) than transmission using smaller and longer waves of the High Frequency (HF) or Very High Frequency (VHF) portions of the spectrum below 300 MHz.
The wireless communication system 100 may also operate in the very high frequency (SHF) region using a frequency band from 3GHz to 30GHz (also referred to as a centimeter frequency band). The SHF region includes frequency bands (such as the 5GHz industrial, scientific, and medical (ISM) frequency bands) that can be opportunistically used by devices that can tolerate interference from other users.
The wireless communication system 100 may also operate in the Extremely High Frequency (EHF) region of the spectrum (e.g., from 30GHz to 300GHz), which is also referred to as the millimeter-band. In some examples, the wireless communication system 100 may support millimeter wave (mmW) communication between the UE 115 and the base station 105, and EHF antennas of respective devices may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate the use of antenna arrays within the UE 115. However, propagation of EHF transmissions may experience even greater atmospheric attenuation and shorter ranges than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency regions, and the use of frequency bands specified across these frequency regions may vary by country or regulatory agency.
In some cases, the wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may employ Licensed Assisted Access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band, such as the 5GHz ISM band. When operating in the unlicensed radio frequency spectrum band, wireless devices, such as base stations 105 and UEs 115, may employ a Listen Before Talk (LBT) procedure to ensure that frequency channels are clear before transmitting data. In some cases, operation in the unlicensed band may be based on a CA configuration (e.g., LAA) in cooperation with CCs operating in the licensed band. Operations in the unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in the unlicensed spectrum may be based on Frequency Division Duplexing (FDD), Time Division Duplexing (TDD), or a combination of both.
In some examples, a base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, the wireless communication system 100 may use a transmission scheme between a first device (e.g., base station 105) and a second device (e.g., UE 115), where the first device is equipped with multiple antennas and the second device is equipped with one or more antennas. MIMO communication may employ multipath signal propagation to increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. For example, the first device may transmit multiple signals via different antennas or different combinations of antennas. Likewise, the second device may receive multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), in which multiple spatial layers are transmitted to the same second device; and multi-user MIMO (MU-MIMO), in which a plurality of spatial layers are transmitted to a plurality of devices.
Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a first device or a second device (e.g., base station 105 or UE 115) to shape or steer an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the first device and the second device. Beamforming may be achieved by combining signals communicated via antenna elements of an antenna array such that signals propagating in a particular orientation relative to the antenna array undergo constructive interference while other signals undergo destructive interference. The adjustment to the signal communicated via the antenna elements may include the first device or the second device applying an amplitude and a phase shift to the signal carried via each antenna element associated with the device. The adjustment associated with each antenna element may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to an antenna array of the first device or the second device, or relative to some other orientation).
In one example, the base station 105 may use multiple antennas or antenna arrays for beamforming operations for directional communication with the UEs 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times in different directions by the base station 105, which may include a signal being transmitted according to different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions may be used (e.g., by the base station 105 or a second device, such as the UE 115) to identify beam directions used by the base station 105 for subsequent transmission and/or reception. Some signals, such as data signals associated with a particular second device, may be transmitted by the base station 105 in a single beam direction (e.g., a direction associated with the second device, such as the UE 115). In some examples, a beam direction associated with transmission along a single beam direction may be determined based at least in part on signals transmitted in different beam directions. For example, the UE 115 may receive one or more signals transmitted by the base station 105 in different directions, and the UE 115 may report an indication to the base station 105 of the signal for which it is received at the highest signal quality or other acceptable signal quality. Although the techniques are described with reference to signals transmitted by the base station 105 in one or more directions, the UE 115 may use similar techniques for transmitting signals multiple times in different directions (e.g., for identifying beam directions used by the UE 115 for subsequent transmission or reception), or for transmitting signals in a single direction (e.g., for transmitting data to a second device).
A second device (e.g., UE 115, which may be an example of a mmW second device) may attempt multiple receive beams when receiving various signals from the base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, the second device may attempt multiple receive directions by: receiving via different antenna sub-arrays, processing received signals according to different antenna sub-arrays, receiving according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array, or processing received signals according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array, either of which may be referred to as "listening" according to different receive beams or receive directions. In some examples, the second device may use a single receive beam to receive along a single beam direction (e.g., when receiving the data signal). The single receive beam may be aligned in a beam direction determined based at least in part on listening from different receive beam directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio, or other acceptable signal quality based at least in part on listening from multiple beam directions).
In some cases, the antennas of a base station 105 or UE 115 may be located within one or more antenna arrays that may support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some cases, the antennas or antenna arrays associated with the base station 105 may be located at different geographic locations. The base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with the UEs 115. Likewise, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.
In some cases, the wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communication of the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. In some cases, the Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate on logical channels. The Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat request (HARQ) to provide retransmission by the MAC layer, thereby improving link efficiency. In the control plane, a Radio Resource Control (RRC) protocol layer may provide for establishment, configuration, and maintenance of RRC connections of radio bearers supporting user plane data between the UE 115 and the base station 105 or core network 130. At the Physical (PHY) layer, transport channels may be mapped to physical channels.
In some cases, the UE 115 and the base station 105 may support retransmission of data to increase the likelihood that the data is successfully received. HARQ feedback is a technique that increases the likelihood that data will be correctly received on the communication link 125. HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), Forward Error Correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput of the MAC layer in poor radio conditions (e.g., signal-to-noise conditions). In some cases, a wireless device may support simultaneous slot HARQ feedback, where the device may provide HARQ feedback in a particular slot for data received in a previous symbol in that slot. In other cases, the device may provide HARQ feedback in a subsequent time slot or according to some other time interval.
The time interval in LTE or NR may be in a basic unit of time (which may for example refer to the sampling period T)s1/30,720,000 seconds). The time intervals of the communication resources may be organized according to radio frames each having a duration of 10 milliseconds (ms), where the frame period may be expressed as Tf＝307,200Ts. The radio frame may be identified by a System Frame Number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots each having a duration of 0.5ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix added before each symbol period). Each symbol period may contain 2048 sample periods, excluding the cyclic prefix. In some cases, a subframe may be the smallest scheduling unit of the wireless communication system 100 and may be referred to as a transmission time interval (T)TI). In other cases, the minimum scheduling unit of the wireless communication system 100 may be shorter than a subframe or may be dynamically selected (e.g., in a burst of shortened tti (sTTI) or in a selected component carrier using sTTI).
In some wireless communication systems, a slot may be further divided into a plurality of mini-slots containing one or more symbols. In some examples, a symbol of a mini-slot or a mini-slot may be a minimum scheduling unit. For example, each symbol may vary in duration depending on the subcarrier spacing or operating frequency band. Further, some wireless communication systems may implement timeslot aggregation, where multiple timeslots or mini-timeslots are aggregated together and used for communication between the UE 115 and the base station 105.
The term "carrier" refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over the communication link 125. For example, the carrier of the communication link 125 may comprise a portion of a radio frequency spectrum band operating according to a physical layer channel for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. The carriers may be associated with predefined frequency channels (e.g., E-UTRA absolute radio frequency channel number (EARFCN)) and may be located according to a channel grid for discovery by UEs 115. The carriers may be downlink or uplink (e.g., in FDD mode), or configured to carry downlink and uplink communications (e.g., in TDD mode). In some examples, a signal waveform transmitted on a carrier may include multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique, such as OFDM or DFT-s-OFDM).
The organization of the carriers may be different for different radio access technologies (e.g., LTE-A, LTE-A Pro, NR, etc.). For example, communications on a carrier may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling supporting decoding of the user data. The carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling that coordinates operation of the carrier. In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates the operation of other carriers.
The physical channels may be multiplexed on the carriers according to various techniques. The physical control channels and physical data channels may be multiplexed on the downlink carrier using, for example, Time Division Multiplexing (TDM) techniques, Frequency Division Multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, control information transmitted in the physical control channel may be distributed in a cascaded manner between different control regions (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces).
A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as a carrier or "system bandwidth" of the wireless communication system 100. For example, the carrier bandwidth may be one of several predetermined bandwidths (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80MHz) of a carrier of a particular radio access technology. In some examples, each served UE 115 may be configured to operate over part or all of the carrier bandwidth. In other examples, some UEs 115 may be configured for operation using a narrowband protocol type associated with a predefined portion or range within a carrier (e.g., a set of subcarriers or RBs) (e.g., "in-band" deployment of narrowband protocol types).
In a system employing MCM technology, a resource element may include one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Thus, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate of the UE 115 may be. In a MIMO system, wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers), and using multiple spatial layers may further improve the data rate of communications with the UE 115.
Devices of the wireless communication system 100 (e.g., base stations 105 or UEs 115) may have a hardware configuration that supports communication over a particular carrier bandwidth or may be configurable to support communication over one carrier bandwidth of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 and/or a UE 115 that may support simultaneous communication via carriers associated with more than one different carrier bandwidth.
The wireless communication system 100 may support communication with UEs 115 over multiple cells or carriers, a feature that may be referred to as Carrier Aggregation (CA) or multi-carrier operation. The UE 115 may be configured with multiple downlink CCs and one or more uplink CCs according to a carrier aggregation configuration. Carrier aggregation may be used with both FDD and TDD component carriers.
In some cases, the wireless communication system 100 may utilize an enhanced component carrier (eCC). An eCC may be characterized by one or more characteristics including a wider carrier or frequency channel bandwidth, a shorter symbol duration, a shorter TTI duration, or a modified control channel configuration. In some cases, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum). An eCC characterized by a wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are unable to monitor the entire carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power).
In some cases, the eCC may utilize a different symbol duration than other CCs, which may include using a reduced symbol duration compared to the symbol durations of the other CCs. Shorter symbol durations may be associated with increased spacing between adjacent subcarriers. Devices utilizing an eCC, such as UE 115 or base station 105, may transmit a wideband signal (e.g., according to a frequency channel or carrier bandwidth of 20, 40, 60, 80MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). A TTI in an eCC may include one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in a TTI) may be variable.
Wireless communication systems, such as NR systems, may utilize any combination of licensed, shared, and unlicensed spectrum bands, and the like. Flexibility in eCC symbol duration and subcarrier spacing may allow eCC to be used across multiple spectra. In some examples, NR sharing spectrum may improve spectrum utilization and spectral efficiency, particularly through dynamic vertical (e.g., across frequency domains) and horizontal (e.g., across time domains) sharing of resources.
The UE 115 (e.g., the second device) may identify a gap period after the downlink portion of the TDD frame. The UE 115 may selectively perform a CCA on a channel of the radio frequency spectrum band based at least in part on the gap period. The UE 115 may transmit at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
The base station 105 (e.g., the first device) may perform a CCA on a channel of the radio frequency spectrum band prior to the downlink portion of the TDD frame. The base station 105 may perform a downlink transmission during a downlink portion of the TDD frame based at least in part on the success of the CCA. The base station 105 may receive at least one of an SRS or a PRACH preamble during an initial set of symbols for an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
Fig. 2 illustrates an example of a TDD frame configuration 200 supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. In some examples, the TDD frame configuration 200 may implement aspects of the wireless communication system 100. Aspects of the TDD frame configuration 200 may be implemented by a base station and/or a UE, which may be examples of corresponding devices described herein.
In general, the TDD frame configuration 200 includes TDD frames 205, with two TDD frames 205 shown as an example and illustrated as TDD frame 205-a and TDD frame 205-b. In some aspects, the TDD frame 205 may be a TxOP, mini-slot, partial slot, subframe, or the like. In some aspects, the TDD frame 205 may include one or more resource blocks. Each TDD frame 205 may include a communication portion 210 (illustrated as a CoT) followed by an idle portion 215. Thus, the TDD frame 205-a includes a communication portion 210-a and an idle portion 215-a, while the TDD frame 205-b includes a communication portion 210-b and an idle portion 215-b. In some aspects, the communication portion 210 can be associated with a wireless device that performs uplink and/or downlink communication for control and/or data information. In some aspects, the idle portion 215 may be associated with a period in which the wireless device avoids communicating on the channel. In some aspects, the TDD frame 205 may be used for communication over one or more channels in a shared or unlicensed radio frequency spectrum band, may have a corresponding bandwidth, and so on.
In some aspects, the TDD frame configuration 200 may be an example of a fixed frame period in a network of frame-based equipment (FBE). As one example, the TDD frame 205 may support industrial IoT communications in a single or multiple carrier environment.
In some aspects, the first device may capture the TDD frame 205 by performing a CCA procedure on the channel. For example, the first device may monitor the channel for a period of time to detect signals and/or traffic on the channel, and if no signals and/or traffic are detected, determine that the CCA procedure was successful and transmit a signal to reserve the channel for the communication portion 210. In general, the CCA procedure may be performed prior to performing communication on the channel (e.g., prior to a downlink portion or an uplink portion occurring during the corresponding communication portion 210).
In some aspects, the first device may perform downlink communications using the entire communication portion 210. In other aspects, the first device may have one or more downlink portions and one or more uplink portions during the communication portion 210. In some aspects, a first device may transmit a signal to a second device, the signal carrying or otherwise communicating an indication of a grant of uplink communication on the second device. For example, the signal may include a grant of time/frequency resources that the second device will use to perform uplink communications. As another example, the signal may simply include an indication of a time at which the second device is to begin performing uplink communications, e.g., an indication of a time associated with the uplink portion of the TDD frame 205. Thus, the first device typically controls the channel during the communication portion 210 and may use the channel for uplink and/or downlink communication with the second device.
In some aspects, the first device may have multiple transmissions within the communication portion 210 (e.g., during a CoT) without performing additional CCA procedures, provided that a gap period between such transmissions does not exceed a defined threshold. Accordingly, the second device may continue uplink transmissions without performing the CCA procedure, provided that the gap period between such transmissions also does not exceed the defined threshold, e.g., uplink communications must begin within a defined period from the first device's last downlink transmission. Aspects of the described techniques provide a mechanism to reduce the number of occasions that a second device must perform additional CCA procedure(s) by piggybacking an SRS or PRACH preamble transmission and FDM the SRS or PRACH preamble with DMRS, uplink control or data transmission(s), and/or other random access transmission(s). In general, the SRS or PRACH preamble may be FDM with DMRS, uplink control or data transmission(s), and/or other random access transmission(s) from the second device and/or from other wireless devices. In some aspects, each wireless device utilizing TDD frames 205 may be preconfigured to implement such techniques and/or may be configured by the network to implement or initiate such techniques as desired.
Thus, the second device may identify a gap period following the downlink portion of the communication portion 210 of the TDD frame 205. In some aspects, this may include the second device determining whether the gap period has exceeded the threshold or has not exceeded the threshold. If the gap period has not exceeded the threshold, the second device may continue to perform uplink transmissions without performing a CCA procedure on the channel. The second device may selectively perform a CCA procedure on the channel if the gap period has exceeded the threshold.
The second device may transmit the SRS or PRACH preamble during an initial symbol set of an uplink portion of the TDD frame 205 after the gap period. In some aspects, the SRS or PRACH preamble may be FDM with DMRS, uplink control or data transmissions, and/or random access transmissions during an initial symbol set. In some aspects, the SRS or PRACH preamble may be FDM on a per tone basis (e.g., using different comb teeth for the SRS or PRACH preamble and DMRS/uplink control and/or data, etc.) and/or on a per interlace basis (e.g., using different interlaces for the SRS or PRACH preamble and DMRS/uplink control and/or data, etc.). In some aspects, piggybacking SRS or PRACH preamble in accordance with the described techniques provides a mechanism in which a second device may initiate an uplink transmission (e.g., SRS or PRACH preamble) during an initial set of symbols of an uplink portion of a TDD frame 205 to minimize a gap period between the downlink portion and the uplink portion and thus reduce the likelihood that additional CCA procedures must be performed.
Thus, the second device may transmit an SRS (or PRACH preamble), which may be multiplexed in the frequency domain with a Physical Uplink Shared Channel (PUSCH) UE (e.g., a different device performing uplink control or data transmission) instead of TDM. This may reduce a sensing gap (e.g., gap period) between SRS and PUSCH and avoid additional CCA procedures.
In some aspects, this may include the DMRS and SRS being transmitted on different comb fingers. For example, DMRS for PUSCH may be piggybacked. The SRS is also front-loaded and may be multiplexed on a different comb than the DMRS. In some aspects, the SRS may be frequency multiplexed with PUSCH data when additional SRS symbols are needed. PUSCH data may be rate matched around the comb occupied by SRS resources.
In some aspects, this may include the SRS being front-loaded and FDM with the data on a different comb. For example, the DMRS for PUSCH may be TDM with SRS (e.g., to avoid SRS and DMRS on the same symbol).
In some aspects, this may include an interleaved SRS design. For example, SRS may be transmitted on a given comb on a given interlace (e.g., SRS and PUSCH/Physical Uplink Control Channel (PUCCH)/PRACH are on different interlaces).
In some aspects, the described techniques may be used with SRS and/or PRACH transmission. For example, the PRACH may be transmitted at the beginning of an uplink portion, e.g., a piggybacked PRACH. In some aspects of a given PRACH format, a defined starting symbol position may be supported. The PRACH may be FDM with other channels by transmitting on different interlaces, different comb teeth, and/or different resource elements. A comb-based PRACH design may be utilized when the PRACH and other channels are multiplexed on different resource elements.
Fig. 3 illustrates an example of a Resource Block (RB) configuration 300 supporting a front-loaded SRS and PRACH, in accordance with aspects of the present disclosure. In some examples, the RB configuration 300 may implement aspects of the wireless communication system 100 and/or the TDD frame configuration 200. Aspects of the RB configuration 300 may be implemented by a UE and/or a base station, which may be examples of corresponding devices described herein. It should be understood that reference to transmitting SRS according to the RB configuration 300 may also refer to PRACH preamble transmission.
In general, RB configuration 300 illustrates two example configurations of RB 305. In general, RB 305 may be an initial RB occurring during the uplink portion of a TDD frame. For example, a first device (e.g., a base station) may perform a CCA procedure on a channel. If the CCA procedure is successful, the first device may capture the channel for some or all of the duration of the TDD frame and perform one or more downlink transmissions during a corresponding downlink portion of the TDD frame. In some aspects, the first device may also use the channel for uplink transmissions from the second device, e.g., the first device may provide a grant or other indication of time and/or frequency resources of a TDD frame for the second device to use for uplink communications. In some aspects, the uplink portion of the TDD frame may span one or more RBs 305.
In some aspects, each of the two illustrated RB 305 configurations includes a plurality of tones (where 12 tones are shown by way of example only and labeled 0-11 on the vertical axis) and a plurality of symbols (where 14 symbols are shown by way of example only and labeled 0-13 on the horizontal axis). Other RB 305 configurations with more or fewer tones and more or fewer symbols may also be used.
A first example RB 305 configuration includes DMRS transmission of 1 OFDM symbol. In general, a first example RB 305 configuration includes multiplexing an SRS with DMRSs from four antenna ports in the frequency domain. For example, a first example RB 305 configuration may include symbols 0 and 1 used as non-uplink symbols 310, e.g., symbols 0 and 1 may be part of the downlink portion of a TDD frame and/or may be part of a gap period between the downlink portion and the uplink portion. During symbol 2, SRS 320 may be multiplexed with DMRS 315 in the frequency domain. For example, DMRS 315 may be transmitted on tones 0,2, 4, 6, 8, and 10 of symbol 2, while SRS may be transmitted on tones 1, 3, 5, 7, 9, and 11 of symbol 2. In some aspects, the DMRS 315 may be transmitted from one or more antenna ports, where ports 1000 and 1001 are illustrated in a first example RB 305 configuration. In some aspects, the FDM technique may correspond to different comb fingers, with DMRS 315 transmitted on comb finger 1 (e.g., on a first comb finger comprising tones 0,2, 4, 6, 8, and 10) and SRS transmitted on comb finger 2 (e.g., on a second comb finger comprising tones 1, 3, 5, 7, 9, and 11). The remaining resources of the first example RB 305 configuration may be for PUSCH 330 transmission, e.g., one or more of tones 0-11 and/or symbols 3-13 may be for PUSCH 330 transmission.
A second example RB 305 configuration includes DMRS transmission of 2 OFDM symbols. In general, the second example RB 305 configuration includes multiplexing the SRS with the DMRS from four antenna ports during two symbols in the frequency domain. For example, a second example RB 305 configuration may include symbols 0 and 1 as non-uplink symbols 310, e.g., symbols 0 and 1 may be part of the downlink portion of a TDD frame and/or may be part of a gap period between the downlink portion and the uplink portion. During symbols 2 and 3, SRS 320 may be multiplexed with DMRS 325 in the frequency domain. For example, DMRS 325 may be transmitted on tones 0,2, 4, 6, 8, and 10 of symbols 2 and 3, while SRS may be transmitted on tones 1, 3, 5, 7, 9, and 11 of symbols 2 and 3. In some aspects, the DMRS 325 may be transmitted from one or more antenna ports, with four ports 1000, 1001, 1004, and 1005 illustrated in the second example RB 305 configuration. In some aspects, the FDM technique may correspond to different comb fingers, with DMRS 325 transmitted on comb finger 1 for symbols 2 and 3 (e.g., on a first comb finger comprising tones 0,2, 4, 6, 8, and 10), and SRS 320 transmitted on comb finger 2 for symbols 2 and 3 (e.g., on a second comb finger comprising tones 1, 3, 5, 7, 9, and 11). The remaining resources of the second example RB 305 configuration may be for PUSCH 330 transmission, e.g., one or more of tones 0-11 and/or symbols 4-13 may be for PUSCH 330 transmission.
Fig. 4 illustrates an example of an RB configuration 400 supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. In some examples, the RB configuration 400 may implement aspects of the wireless communication system 100 and/or the TDD frame configuration 200. Aspects of the RB configuration 400 may be implemented by a UE and/or a base station (which may be examples of corresponding devices described herein). It should be understood that reference to transmitting SRS according to the RB configuration 400 may also refer to PRACH preamble transmission.
In general, RB configuration 400 illustrates two example configurations of RB 405. In general, the RB 405 may be an initial RB that occurs during the uplink portion of a TDD frame. For example, a first device (e.g., a base station) may perform a CCA procedure on a channel. If the CCA procedure is successful, the first device may capture a channel within the TDD frame and perform one or more downlink transmissions during a corresponding downlink portion of the TDD frame. In some aspects, the first device may also use the channel for uplink transmissions from the second device, e.g., the first device may provide a grant or other indication of time and/or frequency resources of a TDD frame for the second device to use for uplink communications. In some aspects, the uplink portion of the TDD frame may span one or more RBs 405.
In some aspects, each of the two illustrated RB 405 configurations includes a plurality of tones (where 12 tones are shown by way of example only and labeled 0-11 on the vertical axis) and a plurality of symbols (where 14 symbols are shown by way of example only and labeled 0-13 on the horizontal axis). Other RB 405 configurations with more or fewer tones and more or fewer symbols may also be used.
A first example RB 405 configures a DMRS transmission comprising 1 OFDM symbol. In general, a first example RB 405 configuration includes multiplexing an SRS with uplink control or data transmission in the frequency domain. For example, a first example RB 405 configuration may include symbols 0 and 1 being used as non-uplink symbols 410, e.g., symbols 0 and 1 may be part of a downlink portion of a TDD frame and/or may be part of a gap period between the downlink portion and the uplink portion. During symbol 2, SRS 425 may be multiplexed with PUSCH data 440 in the frequency domain. For example, PUSCH data 440 may be transmitted on tones 0,2, 4, 6, 8, and 10 of symbol 2, while SRS 425 may be transmitted on tones 1, 3, 5, 7, 9, and 11 of symbol 2. During symbol 3, DMRS 415 may be multiplexed with DMRS 420 in the frequency domain. For example, DMRS 415 may be transmitted on tones 0,2, 4, 6, 8, and 10 of symbol 3, while DMRS 420 may be transmitted on tones 1, 3, 5, 7, 9, and 11 of symbol 3. In some aspects, the DMRS 415 and DMRS 420 may be transmitted from one or more antenna ports, where in a first example RB 405 configuration, ports 1000 and 1001 are illustrated for DMRS 415 and ports 1002 and 1003 are illustrated for DMRS 420. In some aspects, the FDM technique may correspond to different comb fingers, with SRS 425 transmitted on comb finger 1 (e.g., on a first comb finger comprising tones 0,2, 4, 6, 8, and 10) and PUSCH data 440 transmitted on comb finger 2 (e.g., on a second comb finger comprising tones 1, 3, 5, 7, 9, and 11). Similarly, DMRS 415 is transmitted on comb 1 and DMRS 420 is transmitted on comb 2. The remaining resources of the first example RB 405 configuration may be for PUSCH 440 transmissions, e.g., one or more of tones 0-11 and/or symbols 4-13 may be for additional PUSCH 440 transmissions.
A second example RB 405 configures a DMRS transmission comprising 2 OFDM symbols. In general, the second example RB 405 configuration includes multiplexing the SRS with uplink control or data transmission in the frequency domain. For example, a second example RB 405 configuration may include symbols 0 and 1 for the non-uplink symbol 410, e.g., symbols 0 and 1 may be part of the downlink portion of a TDD frame and/or may be part of a gap period between the downlink portion and the uplink portion. During symbols 2 and 3, SRS 425 may be multiplexed with PUSCH data 440 in the frequency domain. For example, PUSCH data 440 may be transmitted on tones 0,2, 4, 6, 8, and 10 of symbols 2 and 3, while SRS 425 may be transmitted on tones 1, 3, 5, 7, 9, and 11 of symbol 2. During symbols 4 and 5, DMRS 430 may be multiplexed with DMRS 435 in the frequency domain. For example, DMRS 430 may be transmitted on tones 0,2, 4, 6, 8, and 10 of symbols 4 and 5, while DMRS 435 may be transmitted on tones 1, 3, 5, 7, 9, and 11 of symbols 4 and 5. In some aspects, DMRS 430 and DMRS 435 may be transmitted from one or more antenna ports, where in a second example RB 405 configuration, ports 1000, 1001, 1004, and 1005 for DMRS 430 are illustrated and ports 1002, 1003, 1006, and 1007 for DMRS 435 are illustrated. In some aspects, the FDM technique may correspond to different comb fingers, with SRS 425 transmitted on comb finger 1 (e.g., on tones 0,2, 4, 6, 8, and 10) and PUSCH data 440 transmitted on comb finger 2 (e.g., on tones 1, 3, 5, 7, 9, and 11). Similarly, DMRS 430 is transmitted on comb 1 and DMRS 435 is transmitted on comb 2. The remaining resources configured by the second example RB 405 may be for PUSCH 440 transmissions, e.g., one or more of tones 0-11 and/or symbols 6-13 may be for additional PUSCH 440 transmissions.
Fig. 5 illustrates an example of an interleaving configuration 500 supporting a piggybacked SRS and a PRACH, in accordance with aspects of the present disclosure. In some examples, the interleaving configuration 500 may implement aspects of the wireless communication system 100 and/or the TDD frame configuration 200. Aspects of the interleaving configuration 500 may be implemented by a UE and/or a base station, which may be examples of corresponding devices described herein.
In general, the described techniques provide a first device to capture a channel of a shared or unlicensed radio frequency spectrum band within a TDD frame. For example, a first device (e.g., a base station) may perform a CCA procedure on a channel and, if successful, capture the channel within a TDD frame. The first device may perform downlink transmission(s) on the channel and/or use the channel for uplink transmission from a second device (e.g., a UE). In some aspects, a channel may have an associated bandwidth 505 that includes a plurality of clusters 510 (where clusters 510-a through 510-m are shown by way of example only). In general, each cluster 510 may support an interlace-based design in which different types of transmissions are multiplexed in the frequency domain (e.g., on different interlaces). For example, the first cluster 510-a may include an SRS interlace 515-a, a PUSCH interlace 520-a, and a PUCCH interlace 525-a. The second cluster 510-b may start with the PRACH interlace 530-a and be followed by one or more additional interlaces (not shown). The final cluster 510-m may include a PUSCH interlace 520-m, a PUCCH interlace 525-m, and a PRACH interlace 530-m. Other cluster 510 configurations may also be used.
Thus, the second device may transmit the SRS (or PRACH preamble) in an SRS interlace 515-a (e.g., a first interlace) of the channel bandwidth 505 and may transmit the DMRS, or uplink control or data transmission, or random access transmission in a corresponding PUSCH interlace 520-a, PUCCH interlace 525-a, PRACH interlace 530-a (e.g., a second interlace) of the channel bandwidth 505.
Fig. 6 illustrates an example of a process 600 to support a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. In some examples, the process 600 may implement aspects of the wireless communication system 100, the TDD frame configuration 200, the RB configuration 300/400, and/or the interlace configuration 500. Process 600 may include a base station 605 and a UE 610, which may be examples of corresponding devices described herein. In some aspects, base station 605 may refer to a first device and UE 610 may refer to a second device, or vice versa.
At 615, the base station 605 may perform a CCA procedure on a channel of the radio frequency spectrum band. A CCA procedure (or other LBT procedure) may be performed prior to a downlink portion of a TDD frame.
At 620, during the downlink portion of the TDD frame, the base station 605 can transmit (and the UE 610 can receive) downlink transmissions. In some aspects, the base station 605 may transmit a downlink transmission based on the CCA procedure being successful (e.g., based on whether the base station 605 captures the channel).
At 625, the UE 610 may identify a gap period after the downlink portion of the TDD frame. Broadly, the gap period may refer to a time period between a downlink portion and an uplink portion of a TDD frame.
At 630, the UE 610 may selectively perform a CCA procedure on the channel. For example, the UE 610 may perform a CCA procedure when the duration of the gap period exceeds a threshold. In another example, the UE 610 may transmit the SRS or the PRACH preamble without performing the CCA procedure when the duration of the gap period is less than the threshold.
At 635, the UE 610 can transmit (and the base station 605 can receive) the uplink transmission. In some aspects, the uplink transmission may include an SRS and/or PRACH preamble transmitted in an initial set of symbols (e.g., the first one or more symbols after the gap period) of an uplink portion of the TDD frame. In some aspects, the SRS and/or PRACH preamble may be multiplexed with the DMRS, uplink control or data transmission(s), and/or random access transmission(s) in the frequency domain during the initial symbol set.
In some aspects, this may include the UE 610 identifying a first comb of resource blocks and transmitting the SRS and/or PRACH preamble on the first comb. The UE 610 may identify a second comb and transmit DMRS, uplink control or data transmission(s), and/or random access transmission(s) on the second comb.
In some aspects, DMRS may be transmitted from one or more antenna ports. For example, the DMRS may be transmitted on a first set of antenna ports during a first subset of an initial set of symbols and from a second set of antenna ports during a second subset of the initial set of symbols.
In some aspects, this may include the UE 610 transmitting an SRS or PRACH preamble multiplexed with uplink data transmissions in the frequency domain during a first subset of the initial set of symbols.
In some aspects, this may include the UE 610 transmitting an SRS or PRACH preamble frequency domain multiplexed with DMRS, uplink control or data transmission(s), and/or random access transmission(s) on different interlaces of the channel bandwidth.
Fig. 7 illustrates a block diagram 700 of an apparatus 705 supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. The device 705 may be an example of aspects of a UE 115 as described herein. The device 705 may include a receiver 710, a communication manager 715, and a transmitter 720. The device 705 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).
The communication manager 715 may identify a gap period after the downlink portion of the TDD frame; selectively perform a CCA on a channel of a radio frequency spectrum band based on the gap period; and transmitting at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. The actions performed by the communication manager 715 as described herein may be implemented to achieve one or more potential advantages. One implementation may allow the UE 115 to avoid additional lengthy CCA procedures to reduce latency and save resources by minimizing the gap period between the downlink and uplink portions of the TDD frame. The communication manager 715 may be an example of aspects of the communication manager 1010 described herein.
The communication manager 715 or subcomponents thereof may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 715 or subcomponents thereof may be performed by a general purpose processor, a DSP, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.
The communication manager 715 or subcomponents thereof may be physically located at various locations, including being distributed such that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, the communication manager 715 or subcomponents thereof may be separate and distinct components, in accordance with various aspects of the present disclosure. In some examples, the communication manager 715 or subcomponents thereof may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof, in accordance with various aspects of the present disclosure.
Fig. 8 illustrates a block diagram 800 of an apparatus 805 supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. The device 805 may be an example of aspects of the device 705 or UE 115 as described herein. The device 805 may include a receiver 810, a communication manager 815, and a transmitter 835. The device 805 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).
The communication manager 815 may be an example of aspects of the communication manager 715 as described herein. The communication manager 815 may include a gap period manager 820, a CCA manager 825, and an SRS/PRACH manager 830. The communication manager 815 may be an example of aspects of the communication manager 1010 described herein.
The gap period manager 820 may identify a gap period following the downlink portion of the TDD frame.
The CCA manager 825 may selectively perform a CCA on a channel of the radio frequency spectrum band based on the gap period.
The SRS/PRACH manager 830 may transmit at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
The transmitter 835 may transmit signals generated by other components of the device 805. In some examples, the transmitter 835 may be co-located with the receiver 810 in a transceiver module. For example, the transmitter 835 may be an example of aspects of the transceiver 1020 described with reference to fig. 10. The transmitter 835 may utilize a single antenna or a set of antennas.
Fig. 9 illustrates a block diagram 900 of a communication manager 905 supporting a piggybacked SRS and PRACH in accordance with aspects of the present disclosure. The communication manager 905 may be an example of aspects of the communication manager 715, the communication manager 815, or the communication manager 1010 described herein. The communication manager 905 may include a gap period manager 910, a CCA manager 915, an SRS/PRACH manager 920, a comb manager 925, a port manager 930, an FDM manager 935, an interlace manager 940, and a data manager 945. Each of these modules may communicate with each other directly or indirectly (e.g., via one or more buses).
The gap period manager 910 may identify a gap period following the downlink portion of the TDD frame.
The CCA manager 915 may selectively perform CCA on a channel of the radio frequency spectrum band based on the gap period. In some examples, the CCA manager 915 may perform the CCA procedure when the duration of the gap period exceeds a threshold. In some examples, the CCA manager 915 may transmit the SRS or PRACH preamble without performing the CCA procedure when the duration of the gap period is less than a threshold.
The SRS/PRACH manager 920 may transmit at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. In some cases, the initial set of symbols includes one or more symbols immediately following the gap period.
The port manager 930 may transmit the DMRS from the first antenna port set during the first subset of the initial symbol set. In some examples, port manager 930 may transmit the DMRS from the second set of antenna ports during the second subset of the initial set of symbols.
The FDM manager 935 may transmit an SRS or PRACH preamble frequency domain multiplexed with uplink data transmissions during a first subset of the initial symbol set. In some examples, the FDM manager 935 may transmit the SRS or PRACH preamble frequency domain multiplexed with the DMRS from the set of antenna ports during the second subset of the initial set of symbols. In some cases, the SRS or PRACH preamble and DMRS are transmitted on different comb of resource blocks.
The interlace manager 940 may transmit the SRS or PRACH preamble on a first interlace of the channel bandwidth and the DMRS, or uplink data transmission, or uplink control transmission, or random access transmission on a second interlace of the channel bandwidth.
Fig. 10 shows an illustration of a system 1000 comprising a device 1005 supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. Device 1005 may be an example of or include components of device 705, device 805, or UE 115 as described herein. The device 1005 may include components for two-way voice and data communications, including components for transmitting and receiving communications, including a communications manager 1010, an I/O controller 1015, a transceiver 1020, an antenna 1025, a memory 1030, and a processor 1040. These components may be in electronic communication via one or more buses, such as bus 1045.
The communication manager 1010 may identify a gap period after the downlink portion of the TDD frame; selectively perform a CCA on a channel of a radio frequency spectrum band based on the gap period; and transmitting at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
I/O controller 1015 may manage input and output signals of device 1005. I/O controller 1015 may also manage peripheral devices that are not integrated into device 1005. In some cases, I/O controller 1015 may represent a physical connection or port to an external peripheral device. In some cases, I/O controller 1015 may utilize an operating system, such as
Or another known operating system. In other cases, I/O controller 1015 could represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I/O controller 1015 may be implemented as part of a processor. In some cases, a user may interact with device 1005 via I/O controller 1015 or via hardware components controlled by I/O controller 1015.
The transceiver 1020 may communicate bi-directionally via one or more antennas, wired or wireless links, as described herein. For example, transceiver 1020 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1020 may also include a modem to modulate packets and provide the modulated packets to the antennas for transmission, as well as demodulate packets received from the antennas.
In some cases, a wireless device may include a single antenna 1025. However, in some cases, the device may have more than one antenna 1025, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.
Fig. 11 shows a block diagram 1100 of an apparatus 1105 supporting a front loaded SRS and PRACH, in accordance with aspects of the present disclosure. The device 1105 may be an example of aspects of a base station 105 as described herein. The device 1105 may include a receiver 1110, a communication manager 1115, and a transmitter 1120. The device 1105 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).
The communication manager 1115 may perform a CCA on a channel of the radio frequency spectrum band prior to the downlink portion of the TDD frame; performing a downlink transmission during a downlink portion of the TDD frame based on the success of the CCA; and receiving at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. The communication manager 1115 may be an example of aspects of the communication manager 1410 described herein.
The communication manager 1115, or subcomponents thereof, may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 1115, or subcomponents thereof, may be performed by a general purpose processor, a DSP, an Application Specific Integrated Circuit (ASIC), an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.
The communication manager 1115, or subcomponents thereof, may be physically located at various locations, including being distributed such that portions of functionality are implemented at different physical locations by one or more physical components. In some examples, the communication manager 1115, or subcomponents thereof, may be separate and distinct components in accordance with various aspects of the present disclosure. In some examples, the communication manager 1115, or subcomponents thereof, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in this disclosure, or a combination thereof, in accordance with various aspects of the present disclosure.
The transmitter 1120 may transmit signals generated by other components of the device 1105. In some examples, the transmitter 1120 may be co-located with the receiver 1110 in a transceiver module. For example, the transmitter 1120 may be an example of aspects of the transceiver 1420 described with reference to fig. 14. Transmitter 1120 may utilize a single antenna or a set of antennas.
Fig. 12 shows a block diagram 1200 of an apparatus 1205 supporting a piggybacked SRS and PRACH in accordance with aspects of the present disclosure. The device 1205 may be an example of aspects of the device 1105 or the base station 105 as described herein. The device 1205 may include a receiver 1210, a communication manager 1215, and a transmitter 1235. The device 1205 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).
The communication manager 1215 may be an example of aspects of the communication manager 1115 as described herein. The communication manager 1215 may include a CCA manager 1220, a downlink manager 1225, and a SRS/PRACH manager 1230. The communication manager 1215 may be an example of aspects of the communication manager 1410 described herein.
The CCA manager 1220 may perform a CCA on a channel of the radio frequency spectrum band prior to the downlink portion of the TDD frame.
The SRS/PRACH manager 1230 may receive at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or the PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
Fig. 13 illustrates a block diagram 1300 of a communication manager 1305 supporting a front-loaded SRS and PRACH, in accordance with aspects of the present disclosure. The communications manager 1305 may be an example of aspects of the communications manager 1115, the communications manager 1215, or the communications manager 1410 described herein. The communication manager 1305 may include a CCA manager 1310, a downlink manager 1315, an SRS/PRACH manager 1320, a comb manager 1325, a port manager 1330, an FDM manager 1335, an interlace manager 1340, and a data manager 1345. Each of these modules may communicate with each other directly or indirectly (e.g., via one or more buses).
The CCA manager 1310 may perform a CCA on a channel of the radio frequency spectrum band prior to the downlink portion of the TDD frame.
The SRS/PRACH manager 1320 may receive at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. In some examples, the SRS/PRACH manager 1320 may receive an SRS or a PRACH preamble from a first device and a DMRS, or an uplink data transmission, or an uplink control transmission, or a random access transmission from a second device that is different from the first device. In some examples, the SRS/PRACH manager 1320 may receive at least one of an SRS or a PRACH preamble and a DMRS, or an uplink data transmission, or an uplink control transmission, or a random access transmission from the same device. In some cases, the initial set of symbols includes one or more symbols immediately following the gap period.
The port manager 1330 may receive the DMRS from the first antenna port set during the first subset of the initial symbol set. In some examples, port manager 1330 may receive the DMRS from the second set of antenna ports during the second subset of the initial set of symbols.
The FDM manager 1335 may receive the SRS or PRACH preamble frequency domain multiplexed with the uplink data transmission during the first subset of the initial symbol set. In some examples, the FDM manager 1335 may receive SRS or PRACH preambles from the set of antenna ports that are frequency domain multiplexed with DMRS during the second subset of the initial set of symbols. In some cases, the SRS or PRACH preamble and DMRS are received on different comb of resource blocks.
The interlace manager 1340 may receive the SRS or PRACH preamble on a first interlace of the channel bandwidth and the DMRS, or uplink data transmission, or uplink control transmission, or random access transmission on a second interlace of the channel bandwidth.
The data manager 1345 may receive an uplink data transmission on the PUSCH. In some examples, data manager 1345 may receive additional uplink data transmissions on the PUSCH during one or more symbols occurring after the initial set of symbols.
Fig. 14 shows an illustration of a system 1400 that includes a device 1405 supporting a piggybacked SRS and a PRACH, in accordance with aspects of the present disclosure. Device 1405 may be an example of or include components of device 1105, device 1205, or base station 105 as described herein. Device 1405 may include components for two-way voice and data communications including components for transmitting and receiving communications including a communications manager 1410, a network communications manager 1415, a transceiver 1420, an antenna 1425, a memory 1430, a processor 1440, and an inter-station communications manager 1445. These components may be in electronic communication via one or more buses, such as bus 1450.
The communication manager 1410 may perform a CCA on a channel of the radio frequency spectrum band prior to a downlink portion of the TDD frame; performing a downlink transmission during a downlink portion of the TDD frame based on the success of the CCA; and receiving at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a demodulation reference signal (DMRS), an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
The network communication manager 1415 may manage communication with the core network (e.g., via one or more wired backhaul links). For example, the network communication manager 1415 may manage the communication of data communications for client devices (such as one or more UEs 115).
The transceiver 1420 may communicate bi-directionally via one or more antennas, wired or wireless links, as described herein. For example, the transceiver 1420 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1420 may also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, as well as to demodulate packets received from the antenna.
In some cases, the wireless device may include a single antenna 1425. However, in some cases, the device may have more than one antenna 1425, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.
The inter-station communication manager 1445 may manage communications with other base stations 105 and may include a controller or scheduler for controlling communications with UEs 115 in cooperation with other base stations 105. For example, the inter-station communication manager 1445 may coordinate scheduling of transmissions to the UEs 115 for various interference mitigation techniques, such as beamforming or joint transmission. In some examples, the inter-station communication manager 1445 may provide an X2 interface within LTE/LTE-a wireless communication network technology to provide communication between base stations 105.
The code 1435 may include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communications. Code 1435 may be stored in a non-transitory computer-readable medium, such as system memory or other type of memory. In some cases, code 1435 may not be directly executable by processor 1440, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.
Fig. 15 shows a flow diagram illustrating a method 1500 of supporting a piggybacked SRS and PRACH in accordance with aspects of the present disclosure. The operations of method 1500 may be implemented by UE 115 or components thereof as described herein. For example, the operations of method 1500 may be performed by a communication manager as described with reference to fig. 7-10. In some examples, the UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may perform aspects of the functions described herein using dedicated hardware.
At 1505, the UE may identify a gap period after a downlink portion of a TDD frame. 1505 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1505 may be performed by a gap period manager as described with reference to fig. 7-10.
At 1510, the UE may selectively perform a CCA on a channel of the radio frequency spectrum band based on the gap period. 1510 may be performed according to the methods described herein. In some examples, aspects of the operation of 1510 may be performed by a CCA manager as described with reference to fig. 7-10.
At 1515, the UE may transmit at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. 1515 the operations may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1515 may be performed by an SRS/PRACH manager as described with reference to fig. 7-10.
Fig. 16 shows a flow diagram illustrating a method 1600 of supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. The operations of method 1600 may be implemented by UE 115 or components thereof as described herein. For example, the operations of method 1600 may be performed by a communication manager as described with reference to fig. 7-10. In some examples, the UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, the UE may perform aspects of the functions described herein using dedicated hardware.
At 1605, the UE may identify a gap period following the downlink portion of the TDD frame. 1605 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1605 may be performed by the gap period manager as described with reference to fig. 7-10.
At 1610, the UE may selectively perform a CCA on a channel of the radio frequency spectrum band based on the gap period. 1610 may be performed according to the methods described herein. In some examples, aspects of the operation of 1610 may be performed by a CCA manager as described with reference to fig. 7-10.
At 1615, the UE may identify a first comb of a resource block on which the SRS or PRACH preamble is transmitted during an initial symbol set. 1615 may be performed according to the methods described herein. In some examples, aspects of the operation of 1615 may be performed by a comb manager as described with reference to fig. 7-10.
At 1620, the UE may transmit at least one of an SRS or a PRACH preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. 1620 may be performed according to methods described herein. In some examples, aspects of the operations of 1620 may be performed by an SRS/PRACH manager as described with reference to fig. 7-10.
Fig. 17 shows a flow diagram illustrating a method 1700 of supporting a piggybacked SRS and PRACH, in accordance with aspects of the present disclosure. The operations of method 1700 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of method 1700 may be performed by a communication manager as described with reference to fig. 11-14. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described herein. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functionality described herein.
At 1705, the base station may perform a CCA on a channel of a radio frequency spectrum band prior to a downlink portion of a TDD frame. 1705 may be performed according to the methods described herein. In some examples, aspects of the operation of 1705 may be performed by a CCA manager as described with reference to fig. 11-14.
At 1710, the base station may perform a downlink transmission during a downlink portion of a TDD frame based on success of the CCA. The operations of 1710 may be performed according to the methods described herein. In some examples, aspects of the operations of 1710 may be performed by a downlink manager as described with reference to fig. 11-14.
At 1715, the base station may receive at least one of an SRS or a PRACH preamble during an initial set of symbols of an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. 1715 may be performed according to the methods described herein. In some examples, aspects of the operations of 1715 may be performed by the SRS/PRACH manager as described with reference to fig. 11-14.
Fig. 18 shows a flow diagram illustrating a method 1800 of supporting a piggybacked SRS and PRACH in accordance with aspects of the present disclosure. The operations of method 1800 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of method 1800 may be performed by a communications manager as described with reference to fig. 11-14. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described herein. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functionality described herein.
At 1805, the base station may perform a CCA on a channel of the radio frequency spectrum band prior to the downlink portion of the TDD frame. 1805 may be performed in accordance with the methods described herein. In some examples, aspects of the operation of 1805 may be performed by a CCA manager as described with reference to fig. 11-14.
At 1810, the base station may perform a downlink transmission during a downlink portion of the TDD frame based on the success of the CCA. 1810 may be performed in accordance with the methods described herein. In some examples, aspects of the operations of 1810 may be performed by a downlink manager as described with reference to fig. 11-14.
At 1815, the base station may receive at least one of an SRS or a PRACH preamble during an initial set of symbols for an uplink portion of a TDD frame following a gap period between a downlink portion of the TDD frame and the uplink portion of the TDD frame, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a DMRS, an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols. 1815 may be performed according to the methods described herein. In some examples, aspects of the operations of 1815 may be performed by an SRS/PRACH manager as described with reference to fig. 11-14.
At 1820, the base station may receive an uplink data transmission on the PUSCH. 1820 the operations may be performed according to the methods described herein. In some examples, aspects of the operations of 1820 may be performed by a data manager as described with reference to fig. 11-14.
It should be noted that the methods described herein describe possible implementations, and that the operations and steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more methods may be combined.
The techniques described herein may be used for various wireless communication systems such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and others. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. The IS-2000 version may be generally referred to as CDMA 20001X, 1X, etc. IS-856(TIA-856) IS commonly referred to as CDMA 20001 xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes wideband CDMA (wcdma) and other variants of CDMA. TDMA systems may implement radio technologies such as global system for mobile communications (GSM).
The OFDMA system may implement radio technologies such as Ultra Mobile Broadband (UMB), evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE)802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE, LTE-A and LTE-A Pro are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE-A, LTE-A Pro, NR, and GSM are described in literature from an organization named "third Generation partnership project" (3 GPP). CDMA2000 and UMB are described in documents from an organization named "third generation partnership project 2" (3GPP 2). The techniques described herein may be used for both the above-mentioned systems and radio technologies, as well as for other systems and radio technologies. Although aspects of the LTE, LTE-A, LTE-A Pro or NR system may be described for exemplary purposes and LTE, LTE-A, LTE-A Pro or NR terminology may be used in much of the description, the techniques described herein may also be applied to applications other than LTE, LTE-A, LTE-A Pro or NR applications.
A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. The small cell may be associated with a lower power base station 105 (as compared to the macro cell) and may operate in the same or a different (e.g., licensed, unlicensed, etc.) frequency band than the macro cell. According to various examples, a small cell may include a picocell, a femtocell, and a microcell. A picocell, for example, may cover a small geographic area and may allow unrestricted access by UEs 115 with service subscriptions with the network provider. A femtocell may also cover a smaller geographic area (e.g., a residence) and may provide restricted access by UEs 115 associated with the femtocell (e.g., UEs 115 in a Closed Subscriber Group (CSG), UEs 115 of users in the residence, etc.). The eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, pico eNB, femto eNB, or home eNB. An eNB may support one or more (e.g., two, three, four, etc.) cells and may also support communication using one or more component carriers.
One or more of the wireless communication systems 100 described herein may support synchronous or asynchronous operation. For synchronous operation, the base stations 105 may have similar frame timing, and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation, the base stations 105 may have different frame timings, and transmissions from different base stations 105 may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operations.
Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an FPGA or other Programmable Logic Device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).
The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and the following claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hard wiring, or any combination thereof. Features that implement functions may also be physically located at various locations, including being distributed such that portions of functions are implemented at different physical locations.
Computer-readable media includes both non-transitory computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. Non-transitory storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, a non-transitory computer-readable medium may include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory, Compact Disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes CD, laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.
As used herein, including in the claims, "or" as used in a list of items (e.g., a list of items accompanied by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such that, for example, a list of at least one of A, B or C means a or B or C or AB or AC or BC or ABC (i.e., a and B and C). Also, as used herein, the phrase "based on" should not be read as referring to a closed condition set. For example, an exemplary step described as "based on condition a" may be based on both condition a and condition B without departing from the scope of the present disclosure. In other words, the phrase "based on," as used herein, should be interpreted in the same manner as the phrase "based, at least in part, on.
In the drawings, similar components or features may have the same reference numerals. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description may apply to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.
The illustrations set forth herein in connection with the figures describe example configurations and are not intended to represent all examples that may be implemented or fall within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration," and does not mean "preferred" or "advantageous over other examples. The detailed description includes specific details to provide an understanding of the described technology. However, the techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.
The description herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (30)
1. A method for wireless communication at a User Equipment (UE), comprising:
identifying a gap period after a downlink portion of a Time Division Duplex (TDD) frame;
selectively perform a Clear Channel Assessment (CCA) on a channel of a radio frequency spectrum band based at least in part on the gap period; and
transmitting at least one of a Sounding Reference Signal (SRS) or a Physical Random Access Channel (PRACH) preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a demodulation reference signal (DMRS), an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
2. The method of claim 1, further comprising:
identifying a first comb of a resource block, wherein the SRS or PRACH preamble is transmitted over the first comb of the resource block during the initial set of symbols.
3. The method of claim 2, wherein one or more of the DMRS, or the uplink data transmission, or the uplink control transmission, or the random access transmission is transmitted on a second comb of the resource blocks.
4. The method of claim 1, further comprising:
transmitting the DMRS from a first set of antenna ports during a first subset of the initial set of symbols.
5. The method of claim 4, further comprising:
transmitting the DMRS from a second set of antenna ports during a second subset of the initial set of symbols.
6. The method of claim 1, further comprising:
transmitting the SRS or PRACH preamble frequency-domain multiplexed with the uplink data transmission during a first subset of the initial set of symbols.
7. The method of claim 6, further comprising:
transmitting the SRS or PRACH preamble frequency domain multiplexed with the DMRS from a set of antenna ports during a second subset of the initial set of symbols.
8. The method of claim 7, wherein the SRS or PRACH preamble and the DMRS are transmitted on different comb of a resource block.
9. The method of claim 1, further comprising:
transmitting the SRS or PRACH preamble on a first interlace of a channel bandwidth and transmitting the DMRS, or the uplink data transmission, or the uplink control transmission, or the random access transmission on a second interlace of the channel bandwidth.
10. The method of claim 1, further comprising:
transmitting the uplink data transmission on a Physical Uplink Shared Channel (PUSCH).
11. The method of claim 1, further comprising:
transmitting an additional uplink data transmission on a Physical Uplink Shared Channel (PUSCH) during one or more symbols occurring after the initial set of symbols.
12. The method of claim 1, wherein selectively performing the CCA on the channel of the radio frequency spectrum band based at least in part on the gap period comprises:
performing a CCA procedure when the duration of the gap period exceeds a threshold.
13. The method of claim 1, wherein selectively performing the CCA on the channel of the radio frequency spectrum band based at least in part on the gap period comprises:
transmitting the SRS or PRACH preamble without performing a CCA procedure when a duration of the gap period is less than a threshold.
14. The method of claim 1, wherein the initial set of symbols comprises one or more symbols immediately following the gap period.
15. An apparatus for wireless communication at a User Equipment (UE), comprising:
means for identifying a gap period after a downlink portion of a Time Division Duplex (TDD) frame;
means for selectively performing a Clear Channel Assessment (CCA) on a channel of a radio frequency spectrum band based at least in part on the gap period; and
means for transmitting at least one of a Sounding Reference Signal (SRS) or a Physical Random Access Channel (PRACH) preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a demodulation reference signal (DMRS), an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
16. The apparatus of claim 15, further comprising:
means for identifying a first comb of a resource block, wherein the SRS or PRACH preamble is transmitted over the first comb of the resource block during the initial set of symbols.
17. The apparatus of claim 16, wherein one or more of the DMRS, or the uplink data transmission, or the uplink control transmission, or the random access transmission is transmitted on a second comb of the resource blocks.
18. The apparatus of claim 15, further comprising:
means for transmitting the DMRS from a first set of antenna ports during a first subset of the initial set of symbols.
19. The apparatus of claim 18, further comprising:
means for transmitting the DMRS from a second set of antenna ports during a second subset of the initial set of symbols.
20. The apparatus of claim 15, further comprising:
means for transmitting the SRS or PRACH preamble frequency-domain multiplexed with the uplink data transmission during a first subset of the initial set of symbols.
21. The apparatus of claim 20, further comprising:
means for transmitting the SRS or PRACH preamble frequency domain multiplexed with the DMRS from a set of antenna ports during a second subset of the initial set of symbols.
22. The apparatus of claim 21, wherein the SRS or PRACH preamble and the DMRS are transmitted on different comb of a resource block.
23. The apparatus of claim 15, further comprising:
means for transmitting the SRS or PRACH preamble on a first interlace of a channel bandwidth and transmitting the DMRS, or the uplink data transmission, or the uplink control transmission, or the random access transmission on a second interlace of the channel bandwidth.
24. The apparatus of claim 15, further comprising:
means for transmitting the uplink data transmission on a Physical Uplink Shared Channel (PUSCH).
25. The apparatus of claim 15, further comprising:
means for transmitting an additional uplink data transmission on a Physical Uplink Shared Channel (PUSCH) during one or more symbols occurring after the initial set of symbols.
26. The apparatus of claim 15, wherein means for selectively performing the CCA on the channel of the radio frequency spectrum band based at least in part on the gap period comprises:
means for performing a CCA procedure when the duration of the gap period exceeds a threshold.
27. The apparatus of claim 15, wherein means for selectively performing the CCA on the channel of the radio frequency spectrum band based at least in part on the gap period comprises:
means for transmitting the SRS or PRACH preamble without performing a CCA procedure when a duration of the gap period is less than a threshold.
28. The apparatus of claim 15, wherein the initial set of symbols comprises one or more symbols immediately following the gap period.
29. An apparatus for wireless communication at a User Equipment (UE), comprising:
a processor for processing the received data, wherein the processor is used for processing the received data,
a memory coupled with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
identifying a gap period after a downlink portion of a Time Division Duplex (TDD) frame;
selectively perform a Clear Channel Assessment (CCA) on a channel of a radio frequency spectrum band based at least in part on the gap period; and
transmitting at least one of a Sounding Reference Signal (SRS) or a Physical Random Access Channel (PRACH) preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a demodulation reference signal (DMRS), an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
30. A non-transitory computer-readable medium storing code for wireless communication at a User Equipment (UE), the code comprising instructions executable by a processor to:
identifying a gap period after a downlink portion of a Time Division Duplex (TDD) frame;
selectively perform a Clear Channel Assessment (CCA) on a channel of a radio frequency spectrum band based at least in part on the gap period; and
transmitting at least one of a Sounding Reference Signal (SRS) or a Physical Random Access Channel (PRACH) preamble in an initial set of symbols of an uplink portion of the TDD frame after the gap period, wherein the SRS or PRACH preamble is frequency domain multiplexed with one or more of a demodulation reference signal (DMRS), an uplink data transmission, an uplink control transmission, or a random access transmission during the initial set of symbols.
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| US11411779B2 (en) | 2020-03-31 | 2022-08-09 | XCOM Labs, Inc. | Reference signal channel estimation |
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| CN112189318B (en) | 2023-10-27 |
| US20190349992A1 (en) | 2019-11-14 |
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| WO2019217734A1 (en) | 2019-11-14 |
| US11582000B2 (en) | 2023-02-14 |
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